[303] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 9 
5. Rocky bottoms below low-water mark. 
6. Stony, gravelly, and shelly bottoms. 
7. Sandy bottoms. 
8. Muddy bottoms. 
9. Free-swimming and surface animals. 
10. Parasitic animals. 
It must, however, be constantly borne in mind that very few kinds 
of animals are strictly confined to any one of these subdivisions, and 
that the majority are found in two, three, or more of them, and often in 
equal abundance in several, though each species generally prefers one 
particular kind of locality. In other cases the habits vary at different 
seasons of the year, or at different hours of the day and night, and 
such, species may be found in different situations according to the times 
when they are sought. The more common and characteristic species 
are, however, pretty constant in their habits and may be easily found 
in their respective stations at almost any time. 
Since those animals that inhabit the shores, between tides, are most 
frequently seen and can be most easily obtained and studied by those 
who are not professional naturalists, I have entered into more details 
concerning their habits and appearances than in the ease of those 
obtained only by dredging. Such species as have not been previously 
named and described in other works will be more fully described in the 
systematic list, to follow this report, and references will there be given 
to deseriptions of the others. 
IL—1. ANIMALS INHABITING THE ROCKY SHORES OF THE BAYS AND 
SOUNDS. 
The principal localities where these animals were studied and col- 
lected are at Nobska Point, just east of Wood’s Hole; Parker’s Point, 
between Great Harbor and Little Harbor, near Wood’s Hole; the neck 
of land north of Wood’s Hole Channel; several localities on Naushon 
and the adjacent islands; and numerous localities on theshores of Long 
Island Sound, as at Savin Rock and Light-House Point, near New 
Haven; Stony Creek; Thimble Islands, &e. 
In all these places the rocks, in a zone extending from near low- 
water mark of ordinary tides to near half tide, are generally covered 
with an abundance of “ rock-weeds,” (Mucus nodosus and F. vesiculosus, ) 
which hang in great olive-brown clusters from the sides of the rocks 
or lie flat upon their surfaces when left by the tide, but are floated up 
by means of their abundant air-vessels when the tide rises, Mingled 
with these are several other alge, among which the green “ sea-cabbage ” 
(Ulva latissima) is one of the most abundant. Below this zone of 
Fucus there is a narrow zone whichis only exposed during spring-tides ; 
in this the Ulva and many other more delicate green and red algie 
flourish. Above the Fucus-zone there is another zone of considerable 
width which is covered for a short time by every tide; and still higher 
